andho

<?php

class Invoice {
  private $_items;
  private $_totalAmount = 0;
  private $_sentDate;

  public function isSent() {
    return !is_null($this->_sentDate);
  }

andho

public function __construct($data) {
  $address = array('name', 'post_code');
  $business = array('name', 'address', 'post_code', 'intro');

  if ($data['type] == 'business') $fields = $business;
  else $fields = $address;

  if (count(array_intersect($fields, array_keys($data))) != count($fields)) {
    throw new Exception("Required data was not supplied to the Address object");
  }